The captain shoots the sea monster with a revolver for at least 13 times. A revolver can go as high as 6 times only.
We see Hadji taking a picture of the sea monster with his finger blocking the lens. Later, when we see the picture, Jonny said to Hadji, "That's a great picture of your thumb!". It is physcially impossible that a thumb is in front of the lens when you're taking a picture. A finger maybe, but it can never be a thumb.
The "Star of Borneo" was sailing under the Dutch flag.
The Quests spot the derelict "Star of Borneo" while flying from Singapore to Sumatra.